Usually compound is used to enclose electronic devices when packaging electronic devices, in order to prevent damage caused by external environment. A conventional configuration is shown in FIG. 1 where a substrate array 10 of a ball grid array (BGA) package is composed of many substrates 12 each having a supporting face for seating semiconductor devices thereon. The middle of the supporting face is installation region 14 for seating semiconductor devices.
It is usual to use two pieces of molds for forming an encapsulation based on simple and cheap compound molding. As shown in FIG. 1, a mold runner or gate 16 is set around comer 12. Plated with gold on substrate 12, the adhesion between it and encapsulation is low. The molding and the hardening thereafter are shown in FIG. 2 where encapsulation layer 18 covers semiconductor device and installation region 14 while mold runner or mold gate 16 has residual compound thereon, which was left by molding processing, and which forms extra encapsulant 20 to be stripped off later. Normally the adhesion between encapsulation layer 18 and installation region 14 is very good while that between mold runner or mold gate 16 and encapsulant 20 is relatively poor, thereby substrate 12 and the electronic devices below encapsulation layer 18 are not subjected to any damage when stripping off encapsulant 20.
One drawback with the above scheme is that the adhesion (integration quality) between encapsulation layer 18 and installation region 14 can't be easily known. The only way to test it is to check by stripping off encapsulation layer 18, resulting in a destructive checking which wastes checked products and is limited to sampling checking, thereby can't assure the good quality of those unchecked products. The present invention is therefore suggested to provide a solution to the problems inherent in conventional schemes of the field.